Lamp bulb



June 17, 1930.

c. REITER LAMP BULB Filed April 21, 1925 Patented June 17,- 1930 UNITED STATES PATENT orrlcr.

CASPAR REITER, F BERLIN, GERMANY, ASSIGNOR T0 GENERAL ELECTRIC COMPANY, A. CORPORATION OF NEW YORK LAMP BULB Application filed April 21, 1925, Serial No. 24, 841, and in Germany September 15, 1924.

To obtain by means of electric. incandescent lamps an illumination of a definite color, particularly an illumination like daylight, use has been made in many cases of colored incandescent lamp bulbs. These colored bulbs have previously been obtained either by coloring the glass of which the bulb is made, or providing the surface of the bulb with a suitably colored glaze or varnish. A disadvantage often found in incandescent lamp bulbs colored in these ways is that when not lighted their color is often disagreeable. This is particularly true of those blue-tinted incandescent lamp bulbs with a coloring so chosen was to produce only white light and intended to give illumination like daylight.

The object of this intention is to avoid these disadvantages and at the same time to make possible a good diffusion of the light and a uniform color. To the attainment of these ends and in accordance with the invention the incandescent lamp bulbs are made with a translucent light .diflusing white outer layer made of opal, milk or frosted glass, of sufii- I cient density to be opaque when the lamp is not lighted, and an inner layer or coating of the desired color.

In Figure 1 there is shown, as an example, one form of such bulb partly in section, in which there is indicated a'translucent light diffusingwhite outer layer (a) of opal, milk, or frosted glass, with a colored inner layer (b) of a transparent or translucent material, preferably glass or enamel. Where the inner layer consists of colored glass, the bulb may Instead of'melting together two layers of the bulb, one may use a bulb made either of white the outer or inner surface frosted, which may subsequently be provided on its inner surface with a colored coating or layer or glaze.

While the colored inner layer in the lighted lamps glves color to the light, the outer light diffusion so that through the action of the bulb there is obtained a uniform colored light. The translucent light diffusing outer layer is ofsuch density that it operates-so filament and having a colored coating and a be finished with a light diffusing coating.

translucent light diffusing glass, or one with,

hand this 8th day of cloudy translucent layer causesthe desired that in the unlighted lamp the colored inner,

hidden from the eye of the observer, and the bulb therefore appears white or nearly white.

The same results can also be attained if, as shown in Figure 2 a colored layer 6 is interposed between an outer light difiusing layer (a) and an inner clear glass envelope (0), or else as shown in Fig. 3 a clear glass envelope (0) has on its outer surface a light difiusing layer (a) and on its inner surface a colored layer Also in this case the colored inner layer can be obtained through a colored coating, such as a coating of a colored glass, or through the application of a layer of colored enamel or glaze.

Finally, the protective and light diflusing layer (a) which covers the colored inner layer (1)) may, as shown in Figure 4, be obtained by applying either entirely or partly a glaze or Varnish coating (03) of a; suitably difierent color. In this way it is furthermore possible to obtain from the bulb special color effects, and if desired, to use for the outer layer a color which is complementary to the color of the inner layer. s

The new bulb may be used not only in electric incandescent lamps, but also in arc lamps having tungsten electrodes, and in gaseous conduction lamps.

What I claim as new and desire to secure by Letters Patent of the United States, is

An incandescent lamp comprising a filament and'a sealed vitreous bulb enclosing said white translucent light diflusing layer outcoating when the lamp is not lighted.

In witness whereof, I have hereunto set my April, 1925. CASPAR REITER. 

